Method and apparatus for controlling conductance of an electronic circuit



Sept. 2, .1947.

w. A.,GIESEKE 2,426,734

Original Filed July 26, 1944 6 Sh'eets-Shee l *Poivm 5000b:

5 v I Pawn? X61 8 I ZJ 7 I v 0 [7 v v //5 v .v 25 2 a INVENTORL Wen/m A 67mm:

Sept. 2, 1947.

METHOD AND APP w A. GIESEKE ARAT US FOR CONTROLLING CONDUCTANCE AN ELECTRONIC CIRCUIT 1 Filed July 2 6, 1944 6 Sheets-Sheet 2 AccEPT Powme Pbwsn llAlAAA INVENTOR.

MENEB A. GIESEKE BYflmLM 6 W Arrow Y3 P 1947- w.,A. GIESEKE METHOD APPARATUS FOR CONTROLLING CONDUGTANCE OF AN ELECTRONIC CIRCUIT I 6 Sheets-Sheet 3 Original Filed July 26,- 1944 INVENTOR; I WfRNER AG/fiE/(i- ML {5W "Sept 1947- w. A. GIESEKE 2,426,734

METHOD AND APPARATUS FOR CONTROLLING CONDUCTANCE e Sheets-Sheet 4 OF AN ELECTRONlC CIRCUIT Original Filed July 26,1944

- INVENTOR. I Wan/m A5152 BYWMM METHOD AND APPARATUS FOR CONTROLLING CONDUC'IANCE p 1947- I w. A. GIESEKE 2,426,734

OF 'AN ELECTRONIC CIRCUIT 4 Original Filed July 26, 1944 6 Sheets-Sheet 5 POWER 1 nvomron 1 1 INQICATOR INVENTOR. WERNER A Gizmrs BY 5 2, a

Sept. 2, 1947. w. A. GIESEKE ,4 METHOD AND APPARATUS FOR CONTROLLING CONDUCTANCE 6 Shets-Sheet 6 OF AN ELECTRONIC CIRCUIT Original Filed July 26, 1944 Ram-2PM INVENTOR. Nam/ERA. G/iJE/(E Patented Sept. 2, 1947 BIETHOD AND APPARATUS FOR CONTROL- LING CONDUCTANCE OF AN ELECTRONIC CIRCUIT Werner A. Gieseke, Danville, IlL, assignor to Samuel C. Hurley, J12, Danville, Ill.

Original application July 26, 1944, Serial No.

546,702. Divided and this application June 2, 1945, Serial No. 597,258

4 Claims.

This application is a division of my co-pending application Serial Number 546,702 filed July26, 1944.

This invention relates to an improved method and apparatus for controlling the flow of current through electronic circuits.

It particularly relates to an electronic circuit controlled by a light sensitive circuit whereby the bias on a plurality of control grids in the electronic circuit are independently and successively changed by the amount of light received by the light sensitive circuit.

While my invention relates to an improved electronic circuit, the use of such an electronic circuit in connection with photoelectric inspection operations is described herein as an example of its many uses. 7

It is particularly directed to measuring, determining, or inspecting external or internal dimensions and surfaces of objects. In other words, my invention is particularly useful in connection with determining the silhouette of an article. Among the objects of my invention are to provide a novel method for control of the circuit for use in connection with:

1. The examination, inspection, and measurement of objects.

2. Checking the outline or scanning the outside and internal surfaces of articles.

3. For measuring and indicating the outside and inside diameters of tubes, cylinders, hollow truncated cones, hollow truncated cylinders, cores through spheres, and the like.

4. For checking annular objects for concen tricity and eccentricity,

5. For inspection of cross-sectional shapes of articles.

6. For determining and indicating shapes such as threads, screws, bevels, anchors, curvatures,

. rounds, etc.

A further object is to provide an improved electronic circuit for use in connection with the'positioning of pieces requiring precise location for inspection or a smooth operation with or with out simultaneously exercising control over the additional operation to be performed on the piece under consideration. For example, in color printing, an imprint is made for each color employed. By means of a machine controlled by my electronic circuit which is responsive only to the amount of light received by a light sensitive circuit, it is possible to position the work and to make each successive printing operation exactly as required, within limits of greater accuracy than can be controlled mechanically by means of stops and similar positioning devices.

A further object of the invention is to provide an improved electronic circuit which may be used in connection with handling and/or inspecting pieces which normally have limber, flexible and easily deformed edges such as paper, box board, film, etc., which must be positioned with accuracy and which tend to distort readily when thrust against mechanical stops or the like and when their position or size is indicated by jets of fluid.

Other uses of the circuit is in connection with inspection of internal and external diameters. The distance between predetermined points on an object and the eccentricity and concentricity of objects such as rounds, bars, pistons, cylinders and the like can also be determined.

My electronic circuit can be used in connection with the machines for sorting objects of various sizes or shapes. I

My invention can be usedin connection with inspection or measurement of conditions of objects which are rotated so as to scan the entire external or internal surface of the object. It can also be used for the continuous inspection of drawn objects such as wires, threads, etc., or with the extrusion of tubes, rods, or other shapes. The purpose may be to detect wear, and, in some, cases, may be used to control the dimension of the piece being formed by controlling themachine making it. I

My circuit may be used in connection with the measurement and control of thickness and other dimensions of paper, films, box board, card board, linoleum or sheet metal.

It may also be used in connection with sorting objects of distinctive markings such as bank checks, etc.

It may be used to control machines for cutting or trimming of various objects such as the page of a book,

Another object of the present invention is to provide an improved inspection electronic circuit which may operate upon specimens in motion Without physical contact between the testing instrumentalities and the specimen.

In general, my invention comprises an electronic circuit comprising at least one amplifying tube responsive to the amount of light received by a light sensitive circuit, at least one control or power tube and at least two control grids and means for independently and successively controlling the bias on each control grid, depending upon the amount of light received by the light sensitive circuit.

' t rance -ne 1' ovides The bias of the control grids is not controlled so much by the intensity of the light received by the light sensitive circuit as by the total amount of light received by the light sensitive circuit. In one of my preferred forms, the intens ity of the light falling upon a phototube or father suitable light sensitive device in a light sensitive circuit is maintained substantially constant; but the amount of light received byjthGyPhQtQFll-bfi is varied by varying the v which receives light. This is usually accomplished by varying the portion of the phototube being placed in shadow by the imaaeof. thearticlel being inspected. V

A further broad aspect of my inyentionis the control of the time of firing oi twoin'd 'ngient control or power tubes through only one light sensitive circuit and the conductance of the power tubes or the time of firing controlled by 1(1) the, amount of light received by the light sensitive r ta (2) yagiiust nethe potentia ontthe cathode circuit of each oij the power tubes by eans. of connectin hec thqdeflci cuit to an d ustab resistor! nc sp cific embpdimeut fath broa l a pe t V o my invention,iustdescri cdf r. m as r g the. mens on o n.. t cl wi hiu a predetermi d ieh ns ns iref to wit. compri i a l a t one .ph q ub,ere. oto bes. re mployed. n .thawci cu fi they.

ld. be c nnectedin para lellsin ehthe. 2

onic devi eis ly responsivet theam u o 1ightreceived by, the light sensitive circuit The li ht sensitive. circuit is. connectede oc n. mohfying tube pr.ei,erab1 .pf. .the. vacuumtype andn especially. the. peutude. type he. plate current caused. by the amplifying tubeuisucontmlled by. the amount of light, received bytthellightlsensitive circuit. The control grids-of a pairvoi; electronic, power or control tubes are connected totheplate.

circuit of the amplifier .in betweenlthela odej Of e. amp ifier. and a loading.itesistorisuch-thatthe. more .currentfiowing. through the amplifier, e K. more the. bias. of, thecontrol grids isdriven. in [a negative direction, The, cathode of each of the control or powertubesis adiustablyconnected. to, a source of, pot en tial and the timenofsfiringl for, each of thepower tubesrelative to theamountlof current. flowing, thmughsthempl yin tube. i

controlled byv individu lly and sepa na.telyladiuste= in the potential placed on the respective cathode;

circuits of thelpower tube. I 7

Normally, when thelightsensitiveldeviceree,

ceives anormal amount of light, v.neitherv..of the...

power tubes are firingor conductinglsincethe.

current flowing. through the loaded ,plate.. .cir cuit of the amplifying tube is such thatlthebiasl On each ofv the power tubes is maintained highlyc negative. As the amount of light.receiyedby the light sensitive device decreases, theicurrent flowing through the plate circuit of the amplifying. tubecdecreases and the bias'on onecfthepower or control tubes reaches such a point thatit is. either neutral or positive and thattubewillvfire.

- 4 j tial to which the cathode circuits of the power tubes are connected and the cooperative arrangement of adjustments and the amount of light 7 received by the light sensitive circuit,vI am able to, vary the tolerance range within which an articlelwill -be testedefor a given specification.

For example, in measuring the diameter of a a round within a given tolerance range, the piece ance by varyi gtheitime of firing of the power 5-tive device. Here, again, this particular embodi 0 ing tube is connected to the As the light on the light sensitive circuit. is fur- 5 ther reduced, in like manner the second power tube will fire. Thus, it is seen thatthe greater the difierential in potential in a negative direc-" tion' between the respective cathodes of thepower 1 tubes, the greater the. time between which thevo tubes will be successively fired, and vice versa, the closer the relative potential 'of"the"cathode c'ircuit of each power tube 'is'adjusted, the closer in point of time the power tubes will 'fir 'ei" y this independent adjustment of thepoten-f veration, one of the will, only be good if it falls within the limits of" .thetolerant'zgrange or within thetime period By providing suitable relays and switches and indicating devices, I am able to indicate when apiece comes Within the required tolerance range and when it falls outside'the tolerance range and; am able to vary the tolerubesa 7 Another modification of the above specific embodiment is the use of a power tube in which there are two control grids, the control grid of one being connectedadjustab;ly to a resistor-in the" anodecircuit of the amplifying tube and the other control grid adjustably connected to the resistor in the plate circuit of-a second amplifyingtube, both of the amplifying tubes connected 7 a to a common light sensitive circuitand---the amount of amplification ofeach depending opens the amount *of light receivedby the light sensitive circuit? Inthis' case, the; power tube-willonly firewhen the; bias on each of the control grids is driven sufficiently positiveand either of the control grids maybe driven independenltly in a negative direction'so asto prevent the' fir ing of the power tube. In thisdevice and'opcontrol grids is rendered posi= tive and the tube will-fire; As the; amount .of" light is still further changed in the same three-- tion,'the first control-will then be'rendered positive and the tube will no longer fire; Thus, the-- .length-ofltime that the power tube will 'condu'ct--' or will continue to fire is, cont-rolled' by independently controllingthe bias on each-control-electrode or. grid, which, in turn, is dependent uponthe amount of-light received by the light sensiment is particularly applicable -in'theinspection operation wherein it is desired to have a means for independently varying-the tolerance.

In another specificembodiment similar to; the

fir-st specific: embodiment discussed, two power tubesare provided and-twoampliiying tubes-are; provided. The first power tube is "controlled-bythe amount ofeurrent fiowi-ng through thelcaded plate. circuit of. the,-first -ainpli-fying tube in --the same manner as discussed in the firstemacon'dition that it is conducting the maximurn current the second power tube cannot conduct But when thefsecond' amplifying tube s" current ,is cut off 'o'r greatly reduced because itscathode' circuit has had placed uponit a high positive potential due to a large amount "of lightreceived by the light sensitive circuit, the second power tube will fire. Here, again, the firing of two independent power tubes are separately and successively controlled. The same principle just discussed could also be used when employing only one power tube, in which case, the control grid of the second power tube becomes the second control grid of the first power tube.

In another embodiment of my invention, the use of a plurality of phototubes and light sensitive devices in a light sensitive circuit and by the use of a plurality of power tubes, each controlled and adjusted and independently fired, I provide a system for selecting or indicating the size of different sized articles fed into the inspection zone of the photoelectric inspection operation.

Throughout the description, I have referred to causing or driving the potential or bias of the control grid in a positive direction so that the tube will ionize, fire, or conduct. Depending on the operating characteristics of the tube, the tubes will conduct when the bias on the control grid is slightly negative, say, a negative potential within about five volts. I therefore mean by a positive bias at least sufficient low negative bias for the tube to conduct although the bias may be positive or slightly negative within the operating characteristics of the tube.

I have also referred to firing of a tube which means either causing a tube to conduct or ionize but the term is applicable to either vacuum tubes or tubes of the gas-filled, arc discharge type since both types may be used in my invention.

Other embodiments of my invention will become apparent by referring to the following drawings in which Fig. 1 illustrates a method and device for independently controlling the successive firing of two power tubes.

Figure 2 is similar to Figure 1 and also a relay switch system which may be used for accepting or rejecting articles.

Fig. 3 is a modification of my invention illustrating the use of only one power tube and two amplifying tubes connected to only one light sensitive device.

Fig. 4 illustrates the principle of my invention using two power tubes and two amplifiers, all controlled by one light sensitive circuit with one of the amplifiers having its control grid connected to the ground or what is known as the cut-oif position.

Fig. 5 is similar to Fig. l, showing the use of only one power tube controlling two control grids in that power tube.

Fig. 6 illustrates electronic circuit particularly suitable for indicating the siZe of various sized articles.

Fig. '1 illustrates an optical system which may be used in connection with any of the Figs. 1 to 6, and also shows a specific method for accepting and rejecting an article, depending on whether or not the article meets the required specifications.

Figs. 8 to 12, inclusive, illustrate diagrammatically some of the types of inspections that may be made by my device.

Referring to Fig. 1, a light sensitive device 3, shown as a phototube, is connected .to a source of positive potential at a point t and negative potential at point 5. The cathode of the phototube is connected to the ground 6 through the resistor E. An amplifying tube 8 preferably of the pentode type, although other suitable types may be used, has its control grid 9 connected to point It between the phototube 3 and the re sistor I in the light sensitive circuit. The operating voltages and current for the amplifying tube 8 are provided by connecting the source of potential having its positive potential at H and its negative potential at l2 through the dividing resistors l3, l4, and I5, and connected to the ground at E6. The plate circuit of the amplifying tube 8 is connected to the positive source of potential H through the loading resistor ll. When no or very little light is received by the phototube 3, the potential on the control grid 9 is substantially that of ground and the cathode of tube 8 is adjustably connected to resistor l5 at a potential substantiall above ground and the amplifying tube 8 conducts little or no current.

-As tube 3 receives more light, it places a greater positive potential on the control grid of tube 8 and the less the negative bias, the greater the current which flows through the plate circuit containin resistor ll. Thus, b connecting the control grids l3 and I9, respectively, of tubes I and 2 to point 26 in between the plate of tube 8 and the loading resistor 11, the control grids i8 and i9 have their bias driven in a negative direction when more current flows through the plate circuit of tube 8. If sufiicient current flows through the anode or plate circuit of tube 8, tubes l and 2 will be unable to conduct. The control grids l8 and ii] are respectively connected through limiting resistors 2| and 22 to the line 23 connected to point 29 in the plate circuit of tube 8, The purpose of limiting resistors is to limit the amount of potential that can be placed upon the control grids l8 and I9.

The control tubes I and 2 are preferably of the gas-filled arc discharge type, although other types may be used within the scope of my invention. The cathode and shield grids of these tubes are connected together as shown. The cathode of tube l is connected to an adjustable resistor 2d. The adjustable resistor 24 is connected to a relatively high positive potential by being connected to position terminal H. The adjustable resistor Ed is connected to a ground 25 through the dividing resistor 26. The power tube 2 has its cathode circuit connected to an adjustable rheostat 2'! at a point which is relatively more negative than the point where the cathode of tube l is connected to the adjustable resistor 24. The adjustable rheostat 21 is connected to terminal ll through dividing resistor 29. The potential and current for tubes l and 2 are provided by connecting the cathodes of each tube to a power source 30 to which is also connected the anode circuits through the indicators 3| and 32. The indicators 3| and 32 may be of any conventional type such as bells, flags, meters of all kinds, etc. The indicators are only operated when tubes l and 2 are conducting.

To describe one operation of this circuit, I will consider it first when no light reaches the phototube 3 or, in other words, phototube 3 is placed in shadow by the piece undergoing inspection. In this case, the amplifying tube 8 is non-conducting, the power tubes l and 2 are conducting, since there is no current flowing through the plate circuit of the amplifying tube 8. When no current is. flowing through the plate circuit, the control grids l3 and IQ of the tubes l and 2, respectively, are connected, in effect directly to the positive source of D. C. potential at H, whereas the cathodes are connected to the adjustable resistors 24 and. 21 at a point lower in positive po- 7 tentialthdnbointJ-l; Therefore, the bias onzeachofv the .controlgridsissufficiently positive to rem.- dertubes l audlZ conductive. As'photot-ube 3-recei-vessmore light; the system will reach such a point that s u-ihcient current flows through the plate circuit of thetube 8 that anegative potentialfwil bepiaced .On the. control grid I 8 of: tube I so as to decreaseor. stop the flow of current. in: the-plate circuit of'tu-be land the powerv tube I ceases sconductingzi As the phototube 3 receives more light, the system will reach such a point thats ificient urr nt W ll flowthrough the p t circuit; of theamplifying tube 8 so as to .drive the biasoncontrol grid I9 of tube ,2 sufficiently negative, or-,.in other words, drive the potential of the grid ltsbelow the-point to which the cathode of tube 2 is connected to the adjustable re. sister 2-] soitha-t tube 2 Will. cease to conduct. Thus, when the tube :2 receives the maximum amount of. light; neither ofthe tubes 1- and -21-are conducting; willconduct first and'as the light is further decreased, tube ",5 will then conduct.

the application of my device on inspection operations the inspection operation is conducted such. that the. piece: is good between the time-of conducting of tubes 1: and- 2 if the phototube 3' ei es the proper am o i h i cant ll be seen that as the amount of light on tube. 3, decreases; the timeoi firing of tubes 2 and i liber ind p nd n ly a t d y h re ist r 24, and 22?. If the maximum amount of light-is anthetu-betcand it is desired to have tube 2 re wit -J st li h the. potential: th th de 0:" tube 2'is adjusted in a negative direction by means of adjustable resistor 2:7. Likewise, ifit is desired tog-have; tube .5 fireforqa very large decrease in amount-of light: received by tube the. adjustable resistor EA-is adjusted so as. to connect the :catln ods; of tube I ate higher positive potential than isshown onitheadrawing. Thus, the length: of time. between-tube 2 firing: and tube I firing'as the. amountof. light on tube 3' varies, may be changed; by adil-isting the resistors 2t and; 21;

Thisginethodiand'means for adjusting time for.

firing. and the time. the. tubes will cease. toffire proyidessasnoyel. method and device for control-.- ling the-tolerancez in measuring a. dimension of.

alsp ecimen; .Th-is can be more readily explained by referiiingto:Eig.g2;. Throughout the descriptiorrand illustrations, the same numbers used in: the various-figures Will applyrto the same or equivalent.partsrflorv thesalse of. simplicity.

fifiierringstou'ig. 2, the anode or platecircuits of tubes 1- andIZ; are connected respectively to relay 'coilsfidgand ii. Relay coil 33' is positioned toractuate thezrelay switch siiand relay coil: 3 is positioned. to actuate the relay switch 35. The position .ofnthe relayswitches shown in Fig. 2 are for. the maximum light received by the phototube 3. of Fig; l. Whenthe tube direeeivesinaximum light; neither. power. tube l nor power tube Zfare fired and therelay coils and 3d are not energizeda-nd the relay switches 35 and stare positioned such that the reject indicator or se-.

lecting; means 3.? has its circuit closed. In inspectingspecimens' for a givendimension Within.

arpredeterminedtolerance range, if the, dimension is proper; it wiilshadow: tube 3 suchthat tube 3-Willf receive only-sufficient light for the power As the light is decreased, tube 12:

a t-slight; decrease in amount of equival nt, embodiment. of; invention. mplifyin tube 3d,. similar: to: the amplifying; tube 8 of Big; 11-, has its control-grid Azllconnected object is too:lar e, it

between the successive firing. of; tubes. .2; and 1-. gives a tolerance within: whichthe "piece amayxbe accepted, .andiif: thepiece-is 1120c large; it." will: be rejected because. tube 3;- receives too littiezlight andthe power tube: l? fires, opening the accept.

circuit andclosing. the reject circuit: andlifz. the;

piece is. too smaiL. it. will: reduce 1 the; lightaonr. 3.

sufiicientiyto fire tube 2; and the rejectcircuit: is closed; Thesamecircui shown .in Fig. 12:,i

stead .of accepting; a. piecewithina definite olerancerangc, could lbfiiusfiditolindlflfitfi: two difl'ere ent sizes .ofarticles-and-iifimore-sizes; of: articles a. are desired,- additionalzindicating means .tflzand:

stcould beused to indicate idiiierent sizedarticles;

The: remainin part of the. drawing Fighter 2 which has not been described. above is exactly the sameas the.:correspondingportion; in :Eigure 1.

and the sameznumeiiaishave been applied; This. portion..corr sp nding to Figure. 1 operatesinthe same manner as that described. in: connection:

with the description: forrEigure-l; V

Fig. 3 shows another, although. not necessarily to point Hi Which-issalsoiconnectedi to. then-point lain a' similar-manner that the control'gridt of tube 181s connected'toipointr jfifilllFigl 11. The

amplifying tube 39 is connected directly torthie positive source 0t 13.. .C. potential at: terminal tube Z'rtobe-fired; which willactuate the relay switch .36 open-ingtherejectcircuit and the aeceptrcircuit. Withinthetolerance range,

lesslightmaybe received but-the accept circuit closing V anode of tube: 4 1.

42; having its negative terminal: at. point. 43; Suitable dividing resistors 44 and 45 andxduare. provided togive' the :proper operating and voltage potentials for the amplifying tube 352; Wheni-nolight is on tube 3, the controllgrid: oftube' 39. is. substantially that of. ground; whereas the cathode of; tube. 3941s maintained: at; substantially about ground 'and. the tube 39 conducts In a similar-manner, an.

little or no current. amplifying tube-dlzhas its plate circuit connected to a source 'OfIDLCI potentialhavingits positive terminal; at 592 and: its negative terminal at .50 and: the.- operating current? and; plate voltages are vmaintained through dividing resistors 51:, 52,- and 53, connected to the ground atiidi Likewise; the control grid-4351s.connectedto point: H, and when; there is substantially no light'zon =phototube 3, its potential is substantially. that. of' ground, whereasthe cathode of tubeAl: is connected: to

axpoint substantially above. ground: and no. or

very little current will flow through to tubeAT'. A powerztube-Eifi, similar to tubes 1 and-2.01 Fig. 1, contains two control; grids 56: and: 51: The cone trol. grid:- is. connectedthrough. limiting: resister: 53* tov adjustablecontact point 59 to the adjustable loadingzresistor 5B which is connected between the source of D. C. potential 49 and the The. controlgrid 57 oftube 55* is. connected through loading. resistor- 6| to the adjustable contact point fizcancbthe adjustable loadingwfis whichds connected between-.thecathode. of tube 319. andzatheadjustable: resistor 46;

Thus, itis apparent that when. the tubefl; is:- rendered.- substantially. noneconducting, .the. con trol grid 55: of T tube .55: is.- connected to asource. ofpositive. potentialhigher. than the cathodeof" 5.5f is connected at arela- I tively. low negative potential between'theposb tube. 55; since the tube 9 tive terminal 42 of the direct current source of potential and a ground M and also between the dividing resistors 65 and st. As the amount of light increases on tube 3, the amplification of tube Ail increases and the current fiowing through the resistor increases and a point will be reached due to the current flowing through the reistor that the control grid 55 of the tube 55 will be driven sufilciently negative as to prevent tube from firing, even though sufiicient positive potential were placed on control grid '5. The control grid 5'? is maintained sufficiently negative in respect to the cathode of the tube 55 when no current is flowing through the tube 39 that this bias itself can prevent tube 55 from firing even though the positive potential on control grid is relatively high. However, as tube 3 receives more and more light, the current flowing through the cathode circuit of tube 38 tends to drive the bias on the control grid 5? in a positive direction which will overcome the negative potential of the cathode which is connected. at point 5? such that the tube 55 will fire providing a proper potential is maintained on control grid 5%. Thus, as tube 3 receives more and more light, it tends to drive the bias on control grid 56 in a negative direction and the bias on the control grid 5'? in a positive direction and there is only a certain time period that the bias on both grids is sufiiciently positive as to permit tube 55 to fire.

In a typical operation of my device, I will assume that maximum light is received by tube 3. In this case, the maximum current is flowing I through tubes 35 and 47, and the bias on the control grid 5'5 is maintained relatively high in a positive direction, whereas the bias on grid 55 is maintained in a relative low negative direction and thus the tube 55 will not fire. As the tube 3 receives less light, it will reach a point depending upon the point of contact of the grid circuit to the adjustable rheostat til such that the bias on 53 will become suificiently positive so that the tube 55 will fire. The tube 55 Will continue to fire with further decrease in light, depending upon the point of contact 52 on adjustable rheostat 63 until such a point that insufiicient current flowing through the amplifying tube 39 causes a sufficiently negative potential to be placed on the control grid E'lthat the bias becomes negative and the tube 55 will cease firing. Thus, in passing from maximum light on tube 3, there is only one range of the light received on tube 3 which will permit tube 55 to fire or conduct a current and it is only when the tube 55 is conducting that the indicator 68 is actuated. Therefore, if the electronic diagram shown in Fig. 3 is used to indicate the size of a piece, it is only of the proper size as long as tube 55 is firing. The tolerance within which the piece is good depends upon the length of time the tube '55 will fire which, in turn, depends upon the amount of shadow cast on tube 3 by the image of the piece undergoing inspection. The tolerance can be increased or narrowed by changing the setting of the adjustable connection 62 attached to the resistor 63 and the adjustable point 59' attached to the resistor 30. Furthermore, by this adjustment, the minimum tolerance, as well as the overall tolerance can be individually controlled.

Referring to Fig. 4, amplifying tube 8 and power tube I are connected in the same manner as the corresponding tubes of Fig. 1. The control of tube l by tube 8 is similar. The cathode of tube l is connected to the adjustable resistor ll 10 at point 12. The control grid l8 of tube I is connected through limiting resistor 2| in the line 23 to the point 20. With the phototub 3 completely in shadow, the bias on the tube 8 is adjustable such that no current flows through the amplifying tube 8. As the tube 3 receives more light, current flows through the anode circuit of tube 8 through the load resistor l1 and when the amount of current reaches the point that the control grid [8 of tube I has its potential driven sufficiently in a negative direction, it will stop the flow of current or greatly reduce the flow of current through power tube I and the point at which the current will cease to flow through tube I is controlled by adjusting the adjustable resistor H so as to vary the negative potential placed on the cathode of power tube l This circuit has an additional amplifying tube connected in a similar manner to the amplifying tube 41 with two exceptions, (l) the control grid 43 is connected to ground 16, and (2) the cathode is connected to the adjustable resistor 53 at point 13 which is directly connected to point ll! of the light sensitive circuit between resistor I and'the light sensitive device 3. This hookup for the amplifying tube 41 is commonly referred to as being connected in cut-off position. The bias on the tube 41, when there is no light on phototube 3, is such that a substantial current fiows through the plate circuit of tube 41 but as tube 3 receives more light, a greater positive potential is placed on the cathode circuit of tube 41 and since its control grid 48 is connected to ground, the bias eventually reaches the point where the positive potential on the cathode is such that the tube will cease to conduct current.

Although not shown on the drawing, the point ll may be connected to an adjustable resistor in the line between the phototube 3 and the resistor 5, rather than connecting point ll directly to point H! and thus can be controlled the amplification of tube 48. The power tube 2 is connected to the amplifying tube 41 and its related lines in a similar manner that theamplifying tube 2 is connected in Fig. 1. In other words, as the plate current on amplifying tube 41 increases, it drives the bias on the tube 2 in a negativ direction and thereby reduces the current flow through tube 2 and eventually tub 2 will cease to fire. Again, the time that the tube 2 fires or ceases to fir depending on the amount of light tube 3 receives, may be adjusted b moving the adjustable point 74 along the resistor '65.

The relay switches 35 and 36, controlled by the relay coils 33 and 34, respectively, said relay coils located in the plate circuit of the tubes, respec tively, are shown in such a position that the indicator 68 is not actuated when the tube 2 is firing and the tube l is not firing.

When tube 3 is receiving the maximum amount of light, a large amount of current is flowing through the plate circuit of amplifying tube 8 which places a sufficient negative bias on grid 18 of tube 1 that it will not fire. Under the same conditions, a high positive potential is placed on the cathode of tube 41 and the tube 41 is therefore not firing and the tube 2 is firing since under these conditions the control grid l9 of tube 2 is substantially of the potential of the point 49 and the cathode of tube 2 is at a lower negative potential since it is connected at point 14. As tube 3 receives less light, it will reach the point where the negative bias on the control grid l8 of tube l is reduced to the point that the tube I will fire and the relay switch 35 will be g a-saavce actuated, completing the circuit for the l indica- -torand "theindicator will-indicate that-both of the tubes are filing. tube 3- receives less light, it will' pass through a "period when tubes I' and -2--both are firing but will reach a point when su flicient positive potential is placed on tubeli that the plate current through the tube l! will be increased to the point which will place a sufficiently high negative bia on the control grid 19 of tube 2 that tube 2 will cease-{firing which will open'the relay switch Eat-and the indicator 68 will no1onger1be-actuated Thusyw'ithin the broad principles of my invention, the-indicator i-s -only actuatedduring a definite period in goingfrom maximum ght to minimum light, on:

. tube 3-, and by properly controlling, regulating,

and adjusting the bias on thegrids i8 and I 9 of tubes-I andz, respective-1y, tubes- I and 2 are independently and successively controlled by the amount of lightreceived fro-ma light sensitive circuit such as that embodied in phototube "3. In

such application, 'I can place an article -to be checked for a certain dimension in a. photoelectric inspection zone wherein a beam of light is passed over the article and an image cast upon.

tube If the article is of the right size within the 'predetennined tolerance =range,:whioh may be adjusted bycon-trolli-ng the time that'both tubes I and- 2 are firing, the indicator 68 will .be-ac-tuated. If the article is toolarge, tube 3 will not rec ivesufi'icient Jig-htfor the ind-icator 'ifll to be actuated becausetubei will cease tofire when theamplifier tu-beflil conductssufilcient current to drive the bias on tube 12' in a-negati-vedirectio-n.

Likewise, if the piece is too :small, the tube. 3;

will receive too much light and su'fiici'ent current will :flow through the plate circuit of tube 8 as to-place a high negativebias on control grid oftube I and tube 1 -will not -fire. Thus, the tolerance with-in which-the piece iso f proper dimension can-be controlled by adjusting the time a of firingof tubes I and Z. n

' Referring to Fig. 5; a method and device is shownwherein the principles shown in Fig. 4

"may be used when employing only one power tube. 'In t his case, the-control grid i8, instead'of being-located: in a separate-power tube 5,. is placed impower :tubeJZ. In other words, the .screen grid of power tube instead :of 'beingconnected to the cathode, is connected to. .the line 23. Otherwise, theifunction is' the: same. as forFi-g. 4. The bias-"on. both. grids 'lfixand '9 .must. be 'suiliciently positive for :theindicator .to be actuated. If either zone of them isidriven todmuchsin anega- :tive .directiomithe. indicator would not .be .actu- .ated. Thus, .in checking the dimension of the piece, thew-piece :i only good as longv as it controls the amount. of light on tube 3 such that the bias on tubes I8 .and'lS is..-.sufiiciently.positive to that of the cathode that the tube 2. will fire.

Referring to Fig. 6, another modification employingthe broad :principles...of .myxiinvention'is shown. 'Phototu-besia, I59, andztiizare connected in parallel' between. .the positive terminal .4. and

'the ground 6. The control grid 9 -.of the tube 8 is connected' to :a point. between resistor l and the tubes 3', 73, and: 8-18. Loading resist-or I51: provides-the placing of anegativebiasonlthe control gridslt, 1.9 and slot the phototubes .2, and 18', respectively, to which are. connected-indicato-rsfsl i82, and. 33, respectively.

Amplifying. tube .8 has .its operative voltages provided by dividing resistors i3, 14 and I6.

Inamanner similar to. that describedifor Fig. 1,

:jecti-ng anarticle if the tube .3 :as shown.

controlled by the resistors 2 5, 26, and 216", connected toground for thetube l, resistors28,

"21, and 29 are connected to ground 28 for :the

tube2, and the resistors :86, "Si'and'tu. connected to the positive terminal 1 I. The biason the tubes I, 2, and I8 are respectively adjusted and iregulated through the adjustable resistors .24, .21, 'andfi l. The limiting'resistorsll, 22, and :8'8'are provided. This circuitis particularly adaptedsior indicating. size of articles 'fed to the photoelectric inspection zone which vary in size. For :eX--

ample, if the article isxof'the smallest size, it will darken phototube. .3 and by proper regulating of the negative potential of the cathodeof the tube 18 by means of the adjustable resistor 8%, tube 78 willfire actuating indicator 33'. If the tube is of the next larger size, both phototubes 3 andsl'fi will be darkened and in that case,:indicator 82 will be actuated in a sim'ilarmanner. If the article is of the next size, photiotube .89

will be darkened and indicator. Bl will be actuatd. Thus, I have provideda novelsystem for inspecting articles varying sin-size. In general, the principle shown in Fig. 6 is the same as that shown in Fig. 1 and the independent and successive control'of the'firing of the tubes I,2, and 8"! is accomplished inthe same mannen In Fig. 7 is shown a. type of optical'system'which may be used in connection withqany'of the electronic devices heretofore described. In addition, I. have provided a means for accepting, or rethe proper requirements. a

R.eferring-.to- .7, alight source=--92 isprovided and aicon'densing lens 9:! is located onv the optical axis of the light source for projectingpa. beam of; light through the inspection'Zoneracross: the

topoflthe-article"95 beingsinspected. In this case.

-I-.am checking the article *forproper size; The

gproiecting lens 94:; projects an. imagexof the object onto magmfyingmirror i3, WhichxmaYxber of any .suitabletype but is: shownkas convex, and therefleeting magnified image cuts .acrossrthe. photo- In this case-, -if the-Jpieceis exactly theright size, the tube is :receivingzthe properamount :of light which will actuate the power tubes :1 and I9 of Fig.1 in such a manner that the accept circuit 319 shown inrFig. 2 isclosed.

, actuate the valvefitfi;and-:arblast-of controlled 75. spected; iolzientedriirrt .Theaaccept circuit may control; the solenoid valve wfih-andaxblast of air willssend the :articl'eti-ktl to :thezaccept receptacle. If the piece is either too large or too-small, the phototube :3 will not receive the-proper amount of-lightandthe reject circuit 31 shown iniFig. 2 will be closed which will by the-solenoid valverililiwi-ll flow? through therline intothe V block 91! .and 'the .article.will..be r.ejectedbysending itto the-reject'receptacle. Thus, I have illustrated .one way of sorting articles according .to proper .or impropersize. Y AsimiIa-rideivice :canbeused: with the scheme show-min Fig. .6 tor: sorting articles according to size.

Figs: 8-12- show diagrammatically various types I "of inspections thatv may be made using :onevor more: of the; modificationssof the. electronicci-rcuit herein described. Fig. 8 shows a cnethod-wfor simultaneously indicating the position "of two edges 01. amarticle- Inthiscase, .the-;phototubes are; connected. parallel." and thwcontroliis'made .by' the amount" of "light received "by-both of the phototubes shown. Phototubes cc amt :9? in Figure-'8 are .usedtofmake' theta-hove inspection. of

:9 shows anxarticle to the wina xproperimanner for simul- ::the. article: 5&1

article :does not "meet taneously indicating both the length and the dimension of an article. With specific reference to Figure 9, an article [BB is positioned in the V- block it]! against the stop I02 and the phototubes I03 and 104 are used for simultaneously indicating both the length and the dimension of the article Fig. 10 shows the location of a phototube employed to scan an article such as a cylinder wherein the cylinder is rotated in the inspection zone, for example, between the rollers as shown. If the piece is good, the phototubes will receive the proper amount of light during the entire rotation and this can be indicated by any one of the electronic diagrams herein described with specific reference to Figure 10 a cylindrical article I05 is rotated between the roller are and the phototube in! as used for making th photoelectric inspection.

Likewise, Fig. 11 shows the location of a pair of phototubes wherein a round such as a cylinder may be rotated as in Fig. and the eccentricity and concentricity of the inner and outer surfaces as well as the inner and outer dimensions may be determined with specific reference to Figure ll a cylindrical object IE8 is rotated in a manner similar to that shown for Figure 10 and the phototubes Hi9 and [iii are used for indicating photo electrically the eccentricity and concentricit for the inner and outer surfaces as well as the inner and outer dimensions.

Fig. 12 shows how a number or the tubes may be located around the perimeter of the image of the inside diameter such as is shown in Fig. 11 and where the cylinder ill remains stationary and is not rotated. By connecting phototubes H2 in parallel such as those shown in Fig. 6 and by using the wiring diagram of Fig. 5, for example, there would only be one set of conditions wherein all the phototubes shown in Fig. 12 receive the proper amount of light to actuate indicator 68 of Fig. 5.

Throughout the above description, the amplitying tubes may be of any suitable type. although I have shown them as being the pentode type which I prefer to use in my invention. The power tubes may also be of any conventional type but I prefer to use the gas-filled are discharge type as shown on the drawings. The indicators are only shown conventionally but the indicators may be meters, bells, lights, flags, etc, or may be a selecting device or may operate selecting devices wherein the article is routed or classified according to the type of inspection being made on the article.

The above modifications and embodiments of my invention are not to be considered necessarily equivalent, although they all fall within the broad scope of my invention. Furthermore, the description and the drawings are not to be considered as limiting my invention since it is limited only by the following claims.

I claim as my invention:

1. A photoelectric inspection circuit comprising a light sensitive circuit including a photoelectric device, a first amplifying means connected to said light sensitive circuit such that changes in the amount of light received by the photoelectric device cause correspondin changes in the amount of current flowing through the first amplifying means whereby said change in current is caused only by the amount of light received by said photoelectric device in said light sensitive circuit, a second amplifying means comprising a first control grid and a second control grid, said control respective cathode grids operatively connected to the first amplifying means such that said control grids have their respective voltages changed only by said changes in the amount of current flowing through the first amplifying means and only in accordance with changes in the amount of light received by said photoelectric device and said control grids being further biased and further controlled such that they are successively acted upon and each have their respective voltages changed When said photoelectric device receives an increasing amount of light varying from a relatively small amount of light to a relatively large amount of light, and such that each grid i acted upon successively and in reverse order from the first mentioned change in voltage whereby their respective voltages are changed in the opposite direction or potential from said first mentioned change, when the photoelectric device receives a decreasing amount of light varying from a relatively large amount of light to a relatively small amount of light, and an indicating means operatively connected to said second amplifying means for indicating the state of illumination of said photoelectric device.

2. A photoelectric inspection circuit comprising a source of potential, a light sensitive circuit including a photoelectric device connected to said source, a first amplifying means connected to said light sensitive circuit comprising an amplifying tube having a loaded anode circuit, a control grid and a cathode circuit, said first amplifying means connected to a second source of potential, said control grid biased by said light sensitive circuit such that the more light received by the photoelectric device the more the voltage on said control grid i driven in a positive direction, said amplifying tube normally being biased such that the more light received by the light sensitive device the more current will flow through said amplifying tube, a second amplifying means comprising a second and a third amplifying tube connected in parallel, each of said last mentioned tubes is connected out of phase with the first amplifying tube, each of said last mentioned amplifying tube having an anode circuit, a control grid and a cathode circuit, each control grid of said second and third amplifying tubes being connected to the located anode circuit of the first amplifying tube such that the more current flowing through the said anode circuit the more each control grid is driven in a negative direction of potential, each of said second and third amplifying tubes being normally biased by having their circuits connected to a relatively negative source of potential in respect to their control grids so that each of said last mentioned tubes is rendered conducting, said third amplifyin tube having its cathode circuit connected to a more negative source of potential than the cathode circuit of the second amplifying tube such that more current is required to flow through the anode circuit of the first amplifying tube for driving the control grid of the third amplifying tube in a negative direction of potential thereby rendering said third amplifying tube nonconducting, than is required for driving the control grid of the second amplifying tube in a negative direction of potential thereby rendering the second amplifying tube non-conducting,

whereby the respective control grids of the sec-- 0nd and third amplifying tubes have their respective voltage potentials successively changed in a negative direction by said photoelectric device receiving an increasing amount of light varying .troma. relatively amount of. light to a relatively large amount oftlight and whereby said control gridszhave: their respective voltage potentials changed in .a'gpositive direction. successively but in reverse-order from. said first mentioned change, by said photoelectric device receiving a decreasing amount. of lightfvarying froma relatively largeamount. of light to'a relatively small amount. of. light and an. indicating means oper- .atively'connected'tos-aid secondamplitying means.

for indicating thestate of illumination of said light sensitive'device.

3. A photoelectric inspection circuit comprising a source of potential, a light sensitive circuit including aphotoelectric device connected to said source, a first amplifying means comprising a first amplifying tube and. a second amplifying tube, each. of saidamplifying tubes'having an an ode circuit, a controlagrid and i a cathode circuit,

' :eachof. said-amplifying tubesbeing biased by the light sensitive: circuit such that'the :more light received by the said photoelectric device, the more positive is the -potentia1.:;placed on each of said control grids, the cathode circuit of the first amplifying tube having a load resistor connected therein, the anode circuit of the second amplifying tube having a load resistor connected therein,

' a second amplifying meanscomprising a'third amplifying tube-having an anode circuit, acathode circuit and two control grids, said control grids jointly controlling the flow of current through saidthird amplifying tube, one of said latter control grids biased bybeing connected to the loaded cathodeacircuit of the first amplifying tube such that the .-more current that flows "through thexfirst amplifying tube, thegreater the potential onzsaid last .mentioned grid is driven in a positive direction, the other of said control grids in saidthird amplifying tube-biased by being connected tothe' loaded anode circuit of the second amplifying tube: such that the more current that flows through the second amplifying tube the more .negativeis driven the potential on said other" control. grid whereby the first mentioned .contrologridinithe third amplifying tube is driven" ;a. ;positive :direction .for' an increasing amount :of. light receivedby the photoelectric device. and is; driven inia negative direction of potential for -a;idecreasing. amount of light as" received by the photoelectric device and the second mention-ed control glldil ll'z the third amplifying tube is driven ina negativerdirection of potential for an increasing amountxof. light as received by the photoelectric: device 'andin a positive direction for a decreasingzamountiofi lightassreceived by the pho- '1 toelectric devicefand: an indicating means operatively'connectedsto-said second amplifying means :source,-.a 'firstzamplifyin'g meanscomprising a first amplifying tube .andsa :second first/amplifying tubehaving aloaded anode. 1

amplifying tube,

:circuit, a controlgrid and-1a 'ca. hode circuit, said 1&6 control grid being biasedby :the light sensitive circuit such that the more light received. by the photoelectric device, the more said control-gridis driven in a positive'direction of potential; said second amplifying tube having a loaded anode circuit, a controlgrid' and a loaded cathode circuit, said control grid being connected to ground, said cathode circuit of said second amplifying tube being connected to said, light sensitive circuit such that the more light received by said photoelectricdevice, the more said last mentioned cathode is driven in a positive direction of potential in respect to its control grid thereby decreasing thefiow of current through saidsecond amplifyiugtube, a second amplifying means comprising athird amplifying tube and afourth a-mplifying tube, said third amplifying tube havin an anode circuit, a control grid and. acathode circuit, said third amplifying tube being: connected out of phase With the firstamplifying tube such that the more current that. flows through the first amplifying tube the less current will flow through the third amplifying tube,-said fourthamplifying tube having an anode. circuit, a control-grid and'a cathode circuit, andsaidfourth tube being connected 180 .out of phase with said first amplifyin tube such that the more-current fiowingthrough the second amplifying tube the less current will flow plifying tube, and said control grids in the third and fourth amplifying tubes being further biased and further controlled such that when the photoelectric device receives an increasing amount of light varying from a relatively small amountof:

light to a relatively large amount of light, the control grid in the third amplifying'tube is'driven in a negative direction of potential andthe control grid in the fourth amplifying tube isdriven in a positive direction of. potential and suchthat when the photoelectric device receives a decreasing amount of light varying from a relatively large amount of light to a relatively small amount'of light. that the control grid in the fourth amplifying tube is driven in a positive direction of potential and the control grid in the third amplifying tube is driven in'a negative direction of potential and an indicating means operatively connected with said second amplifying .means for indicating the state of illumination of said light sensitive device. Y 7

WERNER A. GIESEKE.

REFERENCES orrnp The following "references are of record in the file of this patent:

UNITED STATES PATENTS Date through the fourth am- Gulliksen .Mar. 12, 1940 

